Compared to vaginal delivery, cesarean birth results in higher maternal morbidity/mortality and medical costs. In 2009, the cesarean rate in the United States was 33%, and it is still increasing. 'Failure to progress in labor' (a.k.a. dystocia)is the leading cause of non-elective (during labor) primary cesareans and directly or indirectly accounts for about 60% of all cesarean deliveries. Management of patients with poor labor progress focuses on the administration of oxytocin, presuming that the power of uterine contractions is inadequate. However, contraction power does not predict labor dystocia. We have developed a noninvasive maternal-fetal monitor that collects both fetal electrocardiographic signals and uterine electrical activity (electrohysterogram, EHG). Using the EHG signal to generate a real-time topographic map of uterine contractile activity, in a preliminary nested case-control study, we demonstrated that the spatiotemporal patterns of the EHG differed significantly between women with normal labor progress culminating in vaginal delivery and those who underwent cesarean for labor dystocia (p=0.003) and predicted mode of delivery (ROC area under the curve=0.91). In this grant application, we propose a larger, prospective cohort study to better define specific spatiotemporal patterns of the EHG that are associated with cesarean delivery for labor dystocia. We will define the test performance characteristics of those patterns that differentiate women who progress to vaginal delivery from those who do not. We propose to also evaluate whether specific (abnormal) EHG patterns predictive of dystocia precede cessation of cervical dilation or only occur once there is an arrest of dilation. Finally, we will explore the use of EHG patterns as a real-time monitor for predicting labor dystocia. Accomplishment of these aims will set the stage for a randomized clinical trial to evaluate the utility of this technology as a tool for not only decreasing the cesarean delivery rat but also reducing maternal and neonatal morbidities associated with protracted labor.